Immune and toxic factors which cause corneal ulceration or corneal opacity will be studied with purified proteins and other biological macromolecules and with herpes simplex virus. Efforts will be made to identify and characterize virus antigens or by-products of corneal cell- virus interaction which may be involved in corneal hypersensitivity and the complication known as disciform keratitis. Escape kinetics of foreign protein of different type and molecular size will be studied. The resultant corneal sensitization from a single exposure to antigen will be examined to determine the nature of local immunity and the long term retention of this sensitivity. Additional studies will be concerned with the inflammatory responses of the cornea to non infectious proteins, viral toxins and bacterial endotoxin. The mechanism of development of toxic damage to the tissue involving polymorphonuclear leukocytes will be studied.